Astrophysics (Index)About


(EMR power reaching a surface)

Irradiance is the amount of electromagnetic radiation (EMR) (quantified by its energy) per unit time (i.e., power) striking a surface per unit area, from any direction. It is conceptually the sum of the intensity (i.e., radiance) from all directions. Typical units:

Spectral irradiance is irradiance per wavelength or frequency.

Further reading:

Referenced by pages:
flux density
radiative flux
Solar Maximum Mission (SMM)
Upper Atmosphere Research Satellite (UARS)
watt (W)